I'm not sure if this is possible for official MAME, but I'd like to see the following feature added to it:

You Right-click a game and you can select the option of "View Zip File Content". I believe the first derivative that had this feature was MAME Plus! eXTended. I saw this feature and liked it a lot. So I had suggested it to mamesick to add it to MAMEUIFX, which he did.